The web formation process is critical in the production of all nonwoven articles. Webs are produced with a dominant fiber orientation in a known manner by textile machines such as cards or garnetts. It is also known to form webs wherein the fibers have a random arrangement by laying down on a moving wire fibers carried by a stream of an inert gas such as air. Typical processes of the latter type include the mixing of melt-blown fibers by high velocity gas streams from separate sources, as in U.S. Pat. Nos. 3,016,599, 3,502,763, 4,100,324 and 4,263,241. Other patents which use gas streams in web formation include U.S. Pat. Nos. 3,670,731, 4,235,237, 2,988,469, 4,102,963, 4,375,447, 3,755,028, 3,010,161, 2,500,282, 2,411,660 and the melt-blown fiber processes disclosed in U.S. Pat. Nos. 3,442,633, 3,497,337, 3,357,808 and 4,604,313. A wide variety of fiber types are disclosed in the foregoing patents, including natural and synthetic fibers and fibers formed from water-insoluble hydrogels including maleic anhydride copolymer gels such as disclosed in U.S. Pat. Nos. 3,901,236 and 4,610,678.
The higher the absorbency of a fiber the more difficult it is to form webs of the material having the requisite softness, flexibility and density particularly when the precursor polymer used to prepare the fibers is in solution. During the web formation process the inherent hygroscopicity of the fibers may cause the fibers to pick up water from the environment with the consequence that if the fibers are over-dried during the process, voids will form in the web and the web will crack. On the other hand, if the fibers are over-wet the web will become brittle during a subsequent curing operation. The resulting web in both cases will have poor integrity and lack the density, softness and flexibility desired.